This invention relates to a method of packaging unvulcanized, solid neoprene pieces.
The term "neoprene" is generally understood in the art to mean homopolymers and copolymers of chloroprene with other ethylenically unsaturated monomers, wherein chloroprene constitutes at least the predominant monomer.
Neoprene is commercially available as unvulcanized, solid polymer in the form of chips, grains, and chunks of various shapes. Purchasers compound commercial neoprene with fillers, stabilizers, pigments, vulcanizing agents, accelerators, and inhibitors in blenders or mixers of various types, the most common being the Banbury mixer. The compounded neoprene is then fabricated and cured. Neoprene pieces are normally delivered to the blending equipment by means of automated equipment, which requires smooth and even flow of material. Because unvulcanized neoprene is tacky, it is necessary to treat its surface so as to reduce its tackiness to prevent agglomeration. This usually means that neoprene pieces are covered with talc.
Commercial neoprene normally is sold in bags weighing 25 kg. While paper bags are normally used, the labor required for opening and emptying the bags and the necessity of disposing of empty bags add cost and inconvenience to an otherwise simple operation. The problem can be solved by using plastic bags, which can be delivered to blending equipment unopened, so long as the type and amount of the plastic material does not adversely affect the properties of cured neoprene articles. It has been found, however, that is is impossible or difficult to heat-seal plastic bags containing talc-treated neoprene pieces. Apparently, the talc interferes with the normal bag sealing process.
It thus becomes necessary to devise another bag closing means, which would not suffer from this difficulty. Furthermore, it is necessary to provide some bag-retaining means, which would allow polymer-containing plastic bags to be stacked on pallets and handled by fork-lifts without sliding off the pallets.